The probe specifically targets the possible ways in which painkiller producing pharma companies, among which are giant Johnson & Johnson, via financial donations and in other ways, have had the mentioned groups - among them CPB - inspire and/or promote "misleading information about narcotic pain-killers". In short: the suspicion is that the companies have paid the organisations money to play up the reasons for using opiate based painkillers (e.g., morphine) or palliative meds that function like opiates, while playing down the salient negative side-effects and risks of such drugs. The background of the probe is said to be "an epidemic of accidental deaths and addiction resulting from the increased sale and use of powerful narcotic painkillers.".

The tie to CPB is thereby established by its well-known and long-term advocacy of effective palliative care and pain-relief. The center's founder Myra Christopher holds the Kathleen M. Foley Chair in Pain and Palliative Care at CPB, sponsored by the company Purdue Pharma, manufacturer
of OxyContin and other palliative drugs. According to the Kansas City Star, CPB is well known for its ties to Purdue Pharma as well as several other pharma companies:

...as recently as last
month, Purdue was a leading sponsor of the center’s annual dinner and
symposium, contributing $25,000 of the $280,000 that the event raised

Myra Christopher is one of the experts mentioned by name in the letter announcing the Senate probe.

Also The Washington Posthas reported about the probe, and a longer version of that article can be read here. A particularly fishy part of the story expanded on there is that, as the probe was announced, The American Pain Foundation, self-described as "the nation’s largest organization for pain patients", and one of the organisations targeted by the probe, announced its own shut-down due to "irreparable economic circumstances". From the bioethics and CPB angle, this becomes extra uncomfortable, since Myra Christopher has held honorary positions in APF.

Further details about some publications/reports of Christopher that have had a role in advocating expanded use of strong painkillers, or to play down the ethical importance of, e.g. addiction risks or calling into question routines for monitoring patients who are on painkillers for such risks, can be found in the second half of the Kansas City Star article, which also contains comment by bioethics researchers Carl Elliott and Summer Johnson McGee.

Both of these hold out that the notion of pain and suffering as a health problem in its own right is fully defensible one. In consequence, pain can motivate medication that brings various health risks – just as risk of dysfunction or death can. However, the Senate probe does not seem to question this general point. Both Johnson McGee and Elliott also point to the practical problems created by a supposed academic and independent institution advocating policies of great financial benefit to certain parties while, at the same time, being funded by these very parties. My own take is that, even if the money does not lead to outright and calculated intellectual dishonesty or fraudulent behaviour, human psychology has to be taken into account. The money arrives because the funding party likes what one is saying and as one becomes increasingly dependent on the financial support, one will (like it or not, conscious or not) become less and less likely to say something else.

Christopher is reported as insisting that the money from Purdue Pharma always has arrived with "no strings attached". It remains to be seen if the Senate probe will unveil information consistent with that claim or not. But even if it did, that does not take away the problem described above, and to me, the problem with CPB financial dependence on the pharma industry grows as the quote hints that Christopher does not realise this elementary point.